Method for determining parameters for controlling an hvca system

ABSTRACT

A method for determining parameters for regulating an HVAC system including thermal elements configured to be regulated by regulation loops, including: simulation in steady state of thermal and electrical behaviour of the modelled HVAC system, computing energy consumption of the modelled HVAC system for different values of physical magnitudes and different values of set points to be applied at an input of the regulation loops; determination of values of set points for which energy consumption of the modelled HVAC system is lowest; simulation in dynamic state of the thermal and electrical behaviour of the modelled HVAC system, computing values of output physical magnitudes of the thermal elements; computation of parameter values of the regulation loops, based on values of output physical magnitudes of the thermal elements and for each of the regulation loops.

TECHNICAL FIELD

The invention relates to the field of command and control of an HVAC(Heating, Ventilation and Air-Conditioning) system or machine. Theinvention relates more particularly to a method making it possible todetermine parameters for regulating such an HVAC system and foroptimizing the energy consumption of this system.

PRIOR ART

The solutions currently implemented for regulating an HVAC system arenot optimal in terms of the performance, reliability and energyefficiency obtained. This is usually due to the fact that the user ofHVAC systems has little knowledge in the fields of energy regulation oroptimization. Specifically, the adjustment of the parameters of theexisting regulation loops of the HVAC systems is often carried out byhabit, which may cause regulation difficulties within the systems(considerable excesses, pumping phenomena, instabilities etc), thesedifficulties resulting in energy losses and risks of breakage of thebadly regulated equipment. Similarly, the operating points are alsodetermined by habit and not on the basis of a perfect control of theprocess: for example, the high floating pressure of the heat pumps isusually determined by a constant difference between the condensationtemperature and the outside temperature.

Tools exist making it possible to achieve good regulation, such as forexample the implementation of advanced algorithms such as predictivecontrol, or energy optimization functions. However, such tools are verydifficult to use for a user who is not an expert in these fields.

SUMMARY OF THE INVENTION

One object of the present invention is to provide a method fordetermining parameters for regulating an HVAC system improving thecommand and control of the HVAC system, making it possible notably toreduce the energy consumption of the HVAC system and to increase theoperating reliability of the system thus regulated.

For this, the present invention provides a method for determiningparameters for regulating an HVAC system comprising thermal elementsdesigned to be regulated by regulation loops, characterized in that itcomprises at least the following steps:

-   -   simulation in steady state of the thermal and electrical        behaviour of the HVAC system modelled by mathematical models of        the thermal and electrical behaviour of the thermal elements of        the HVAC system, computing the energy consumption of the HVAC        system, modelled for various values of physical magnitudes        influencing the energy performance of the thermal elements, and        various values of set points designed to be applied at the input        of the regulation loops,    -   determination of the values of the set points for which the        energy consumption of the modelled HVAC system is the lowest,    -   simulation in dynamic state of the thermal and electrical        behaviour of the modelled HVAC system, computing the values of        output physical magnitudes of the thermal elements,    -   computation, based on the said values of output physical        magnitudes and for each of the regulation loops, of the        parameter values of the regulation loops.

This method makes it possible to determine regulation parameters basedon which it is possible to easily program, without requiring expertiseon the part of the user in the automation, regulation, optimization ordiagnostics fields, the programmable controller or controllers of anHVAC system.

This method makes it possible to manage two aspects: the regulationitself of the system, but also the optimization of the energyconsumption, for example the electricity consumption, of the HVACsystem.

Thus, the more effective command and control obtained by virtue of themethod makes it possible to solve the problems associated with theregulation difficulties, with the energy inefficiencies and if necessarywith the installation of diagnostic functions.

This method finally allows a user who is not an expert in automation toeasily use a regulation of an HVAC system.

During this method, a simulation is carried out in steady state of thethermal and electrical behaviour of the modelled HVAC system. Such asteady state corresponds to a stable state over time of the HVAC system,that is to say a state in which the variations of the signals of thesystem, notably the output physical magnitudes and the control signals,are substantially zero over time (that is to say, for a signal x of thesystem, such that dx/dt=0). In the context of the present document, a“steady state” therefore does not signify a state that is “permanently”present over time, but rather a stable state.

The dynamic state of the modelled HVAC system corresponds to an unstablestate over time of the HVAC system caused by varying the value of asignal on at least one input of the system, that is to say by applying atransitory signal to this input of the system. In the context of thepresent document, a “transitory” signal corresponds to a signal that canvary over time. The dynamic state is therefore a temporary statefollowing a modification on at least one input of the system.

The simulation in dynamic state of the thermal and electrical behaviourof the modelled HVAC system can therefore be carried out by varyingvalues of input signals of the thermal elements of the modelled HVACsystem, the computation of the values of the parameters of theregulation loops being carried out based on parameters of transferfunctions of the thermal elements corresponding to the ratios betweenthe values of the output physical magnitudes of the thermal elements andthe values of input signals of the thermal elements.

The regulation loops may preferably be of the predictive control type.Thus, the method can use techniques of advanced control of the HVACsystem, for example a PFC (Predictive Functional Command) control.

The simulation in dynamic state of the thermal and electrical behaviourof the modelled HVAC system can be carried out by successively applying,on the inputs of each thermal element, signal variations of a step type.

The simulation in dynamic state of the thermal and electrical behaviourof the modelled HVAC system can be carried out for values of the setpoints for which the energy consumption of the modelled HVAC system islowest.

The invention also relates to a method for regulating an HVAC systemcomprising thermal elements, comprising at least the steps of:

-   -   thermal and electrical modelling of the HVAC system by        mathematical models of the thermal and electrical behaviour of        the thermal elements of the HVAC system,    -   definition of regulation loops in the modelled HVAC system,        designed to be used by at least one controller of the HVAC        system, each regulation loop being associated with at least one        thermal element of the HVAC system and taking account of the        physical magnitudes influencing the energy performance of the        said thermal element and the regulation performance of the said        thermal element,    -   use of a method for determining parameters for regulating the        HVAC system as describe above,    -   programming of the controller of the HVAC system based on the        values of the set points and on the values of the parameters of        the regulation loops computed during the method for determining        parameters for regulating the HVAC system.

The thermal and electrical modelling of the HVAC system may comprise atleast the steps of:

-   -   description of the thermal elements of the HVAC system in a        description software associating the thermal behaviour of each        type of thermal element with one of the said mathematical        models,    -   description, in the description software, of hydraulic and/or        electrical links between the thermal elements.

The definition of the regulation loops may comprise the steps ofdescription, in the software, of:

-   -   regulators capable of carrying out a closed-loop regulation of        the thermal elements associated with the regulation loops,    -   sensors for measuring output physical magnitudes of the thermal        elements placed on the hydraulic links, of which the        measurements are designed to be delivered as input signals to        the regulators,    -   pre-actuators associated with the thermal elements and designed        to receive as inputs control signals delivered by the        regulators.

The method may also comprise, prior to use of the method for determiningparameters for regulating the HVAC system, a step of defining ranges ofpossible values of control signals designed to be delivered by theregulators. Thus, the user can specify operating fields of the system.

The simulation in steady state of the thermal behaviour of the modelledHVAC system may also determine values of control signals designed to beapplied at the input of the thermal elements.

The definition of the regulation loops may also comprise a definition ofranges of possible values of the set points of the regulation loops.Thus, the user can specify the operating point or points of the systemfor which the simulations are carried out.

The method may also comprise, prior to the use of the method fordetermining parameters for regulating the HVAC system, a step ofdefining ranges of possible values of the physical magnitudes.

When the controller of the HVAC system is a programmable controller, theprogramming of the controller can be carried out at least by the use ofthe following steps:

-   -   definition of interactions, in a controller programming        software, between algorithms relating to the energy optimization        of the HVAC system based on the said determined values of the        set points and algorithms relating to the regulation of the HVAC        system based on said computed values of the parameters of the        regulation loops,    -   generation of a control program encoding the said algorithms and        the previously defined interactions,    -   loading of the control program into the programmable controller.

When the controller of the HVAC system is a parameterizable controller,the programming of the controller may comprise at least one step ofentering determined values of the set points and computed values of theparameters of the regulation loops into the controller.

The programming of the controller of the HVAC system may be carried outbased on data in which the values of the set points and the values ofthe parameters of the regulation loops computed during the method fordetermining parameters for regulating the HVAC system are encrypted.

The invention also relates to a device for determining parameters forregulating an HVAC system comprising thermal elements designed to beregulated by regulation loops, comprising means for using a method fordetermining parameters for regulating an HVAC system as described above.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be better understood on reading thedescription of exemplary embodiments given purely as an indication andin no way limiting by making reference to the appended drawings inwhich:

FIG. 1 represents schematically an HVAC system designed to be regulatedby a method that is the subject of the present invention;

FIG. 2 represents schematically a regulation carried out for one of thethermal elements of an HVAC system by the method that is the subject ofthe present invention;

FIG. 3 represents the steps of a method for regulating an HVAC system,that is the subject of the present invention;

FIGS. 4 to 6 represent screen captures of the description software usedduring a method for determining regulation parameters and during amethod for regulating an HVAC system, which are subjects of the presentinvention.

Identical, similar or equivalent portions of the various figuresdescribed below bear the same reference numbers so as to make it easierto switch from one figure to the other.

Various portions shown in the figures are not necessarily shownaccording to a uniform scale, in order to make the figures easier toread.

The various possibilities (variants and embodiments) must be understoodto be not exclusive of one another and may be combined together.

DETAILED DESCRIPTION

Reference is made first of all to FIG. 1 which represents schematicallyan HVAC system 10 designed to be regulated.

The HVAC system 10 represented in FIG. 1 comprises an operative part 12formed by the various elements, or various components, of the HVACsystem 10 to be regulated (compressors, valves, heat exchangers,sensors, etc) and a control part 14 comprising one or more controllersin which command and control functions, preferably advanced functions,are designed to be incorporated. These command and control functions aredesigned to regulate the various elements of the operative part 12 ofthe system 10, but also to optimize the energy consumption of theseelements.

Now will be described the regulation and the energy optimization thatwill be carried out for each of the elements of the HVAC system 10 bythe regulation and energy optimization method, with reference to FIG. 2in which an example of regulation and energy optimization carried outfor one of the thermal elements of the HVAC system 10 is described.

In this figure, a thermal element 20, for example a condenser, of theHVAC system 10 is shown. The thermal element 20 receives on an input 22a control signal u designed to drive the thermal element 20. An outputphysical magnitude y of the element 20, for example a pressure or atemperature of the refrigerant output from the element 20, is measuredon an output 24 of the element 20 and will be used for the regulation ofthe thermal element 20. The relationship between the physical magnitudey and the control signal u corresponds to a first transfer functionH₁(s) of the thermal element 20.

For each of the thermal elements of the HVAC system 10, the value of theoutput physical magnitude y depends on the value of the control signal uapplied at the input of the element 20, but also depends on the valuesof other parameters, called external physical magnitudes influencing theenergy performance of the thermal element, and therefore of the HVACsystem. Such external physical magnitudes are for example an outsidetemperature, a temperature of a fluid entering the machine, a flow rate,a load ratio, a delay, etc. In the example of FIG. 2, three externalphysical magnitudes are represented in the form of variables Gext1,Gext2 and Gext3 applied on the second inputs 23 of the element 20. Therelationships between the value of the physical magnitude y and each ofthe external physical magnitudes Gext1, Gext2 and Gext3 correspond tosecond transfer functions H₂(s), H₃(s) and H₄(s) of the thermal element20, the outputs of which are added to that of the first transferfunction H₁(s) in order to obtain the output physical magnitude y.

The regulation of the thermal element 20 is carried out by a regulationloop 26 determining the value of the control signal u designed to beapplied on the input 22 of the thermal element 20 based on the value ofthe physical magnitude y that is applied on a first input 28 of theregulation loop 26, of a regulation set point y* applied on a secondinput 30 of the regulation loop 26, of measurements of the externalphysical magnitudes Gext1, Gext2 and Gext3, but also of certain internalphysical magnitudes of the thermal element 20 influencing theperformance of the regulation of the thermal element 20.

The value of the regulation set point y* is determined by a set pointgenerator 32 which makes it possible, based on the external physicalmagnitudes Gext1, Gext2 and Gext3 but also by at least one portion ofthe internal physical magnitudes of the thermal element 20 (for examplea compressor control) and applied on the inputs 34 of the set pointgenerator 32, to determine the best set point to be applied as an inputof the regulation loop 26 in order to minimize the energy consumption ofthe thermal element 20. For example, for the optimization of the highpressure set point, the physical magnitudes to be taken into account maybe the temperature of the outside air, the control of the compressors,and the low pressure. In the example of FIG. 2, two internal physicalmagnitudes Gint1 and Gint2 are taken into account and applied as aninput of the set point generator 32. The regulation loop 26 carries outthe regulation part of the command and control of the thermal element20, the set point generator 32 forming the energy optimization part ofthis command and control.

The regulation loop 26 can use various types of regulation, for examplea regulation of PID type. However, the regulation loop willadvantageously carry out a regulation of PFC (Predictive FunctionalControl) type, which makes it possible, relative to a PID regulation, touse a dynamic model of the regulation process inside the controller(control part 14 of the HVAC system 10) and in real time producing theregulation loop 26 in order to anticipate the future behaviour of thethermal element 20. The use of a regulation of PFC type is for exampledescribed in the work of J. Richalet et al.: “La commande prédictive.Mise en œuvre et applications industrielles” [Predictive control. Useand industrial applications], Editions Eyrolles.

The steps of the method of regulation and of energy optimization of theHVAC system 10 that is used, making it possible to achieve theregulation of the thermal elements of the HVAC system 10 previouslydescribed and to parameterize the various regulation algorithms usedwill be described with reference to FIG. 3.

First, the user describes, for example in a software used as adescription tool, the operative part 12 of the HVAC system 10. Thisdescription relates both to the architecture of the HVAC system 10, thatis to say to the links between the various thermal elements 20 of theHVAC system 10, and to the intrinsic features of the thermal elements 20and the nominal operating fields of the system 10 (step 102).

The user therefore describes, initially, the architecture of the HVACsystem 10 by choosing, in the software, generic components representingeach of the thermal elements 20 of the system 10 (heat exchangers,valves, compressors, pumps, fans, etc), then by creating the linksbetween the thermal elements (by linking them by pipes, cables, etc).Each of the generic components present in the software corresponds to amathematical modelling of the thermal and electrical behaviour of athermal element of the HVAC system. Thus, the description produced bythe user therefore forms, in the software, a mathematical modelling ofthe general architecture of the HVAC system 10. An example of adescription made by the user is shown in FIG. 4. In this FIG. 4, theHVAC system 10 comprises a first circuit consisting of an evaporator 50one output of which is linked to a first compressor 52. The output ofthe first compressor 52 is linked to an input of a first condenser 54 ofwhich the output is linked to a first expansion value 56. An output ofthe first expansion valve 56 is linked to the input of the evaporator50. This HVAC system 10 also comprises a second circuit formed by theevaporator 50 an output of which is linked to a second compressor 58.The output of the second compressor 58 is linked to an input of a secondcondenser 60. An output of this second condenser 60 is linked to asecond expansion valve 62 an output of which is linked to a pump 64itself linked to the evaporator 50.

Once the general architecture of the system has been described, the userthen describes individually the features of each of the thermal elementsof this architecture of the HVAC system 10.

For this, the description software may comprise a library in which thefeatures of existing elements are stored. The work of the user thenconsists in selecting a reference in the library. This selection may beassisted by filtering functions: the user may for example enterinformation on the element (for example for an exchanger: plates, tubesand grilles, nominal power, name of the manufacturer, etc), allowing himto have access either directly to the element or to a short list ofpotential elements.

If the element is not present in the library, or if the software doesnot comprise such a library, the user may describe the componentcompletely by entering a list of features corresponding to this element(for example, for a plate exchanger: counter-current or co-current flow,the number of plates, the spacing between plates, the corrugation angle,the width and height of each plate, the material of the plates, theempty weight of the exchanger, describe whether the exchanger isthermally insulated, etc). The features to be entered depend on the typeof element (pump, condenser, compressor, etc).

It is also possible to import into the description software a filecomprising the features of the elements to be described, for example inthe form of a table containing several points, that is to say one ormore tables of values giving the values of the output parameters(pressure, fluid flow rate, etc) of the elements of the HVAC systemdepending on the input parameter values of these elements (inputtemperature, power, water flow rate, etc). Such a file may be a libraryfile of DLL type. A link is made between the inputs/outputs of theimported model and the inputs/outputs of the element modelled in thesoftware.

In a variant, this description of the operative part of the HVAC system10 can be made by the user by answering a list of predefined questionsin the description software, each of the questions relating for exampleto one or more parameters of one of the thermal elements of the HVACsystem 10. Such a description of the HVAC system can be made when theHVAC system forms an assembly of finite machines, that is to say an HVACsystem the architecture of which is predefined in the descriptionsoftware and not modified by the user.

Thus, the information that the user enters is easy to obtain andcorresponds to data relating to the elements of the HVAC system 10 thatthe user is able to understand: for example, if the user is arefrigerationist, these data are exchanger references, exchangermechanical features (number of plates, space between plates, length andwidth of the plates, etc), or else data tables supplied by themanufacturers (for example, for compressors, these data tables maycomprise the values of the low pressure, of the high pressure, of theaspiration temperature, of the flow rate of the refrigerant, etc).

The user then describes, in the description software, the command andcontrol of the system, that is to say the regulation loops of the systemmaking it possible to regulate the various thermal elements of the HVACsystem (step 104). Thus, for each regulation loop to be implemented onthe system, corresponding to the regulation loop 26 described above withreference to FIG. 2, the number of which corresponds to the numbers ofthermal elements to be regulated of the HVAC system, the user indicatesthe physical magnitude obtained at the output of a thermal element thathe wishes to regulate, the actuator that he wishes to drive for thisloop and a set point value that he wishes to apply.

For this, the user again takes up the system modelling previouslycarried out in the description software and first of all sets thesensors to the physical magnitudes that he wishes to measure and thatare intended to be regulated. Thus, in the example of FIG. 5, severaltemperature sensors 66 and pressure sensors 68 are placed downstream andupstream of several elements of the system.

Pre-actuators are then positioned on the actuators of the HVAC system 10to be driven, that is to say on the actuators of the compressors 52 and58, of the condensers 54 and 60, and the actuators of the expansionvalves 56 and 62. These pre-actuators are designed to receive at theinput the values of the control signals delivered by the regulationloops. The user then links the sensors 66, 68 and the pre-actuators tothe regulation boxes 70 which will be typed according to the nature ofthe output physical magnitude to be regulated (for example: the box forspeed regulation, for overheating regulation, for pressure regulation,for temperature regulation, for regulation of the pressure difference,etc), but also depending on the desired type of regulation, notably PIDor predictive control. Finally, the user defines, in the regulationboxes 70, the desired operating fields, that is to say the ranges ofpossible values of the set points of the loops (FIG. 6).

In a manner similar to the description of the operative part of the HVACsystem described above, the description of the command and control ofthe HVAC system 10 can be carried out by the user by answering a list ofpredefined questions in the description software, these questions inthis instance relating to the parameters for command and control of theHVAC system 10 to be carried out.

Based on this complete description (thermal elements+regulation loops)of the HVAC system 10 made by the user, by means of the descriptionsoftware, simulations of the modelled system will be used by computationmodules of the software in order to obtain the values of the parametersof the regulation loops from which it will be possible to program thecontroller or controllers of the control part 14 of the HVAC system 10in order to ensure the command and control of the HVAC system 10, and ofthe parameters of the set point generator 32, comprising notably thevalues of the optimum set points intended to be applied as an input ofthe various regulation loops and making it possible to optimize theenergy consumption of the HVAC system 10 by minimizing it.

Specifically, for each regulation loop, the user can describe set pointsof fixed values. However, these fixed values are not usually optimal interms of energy consumption of the HVAC system, notably because of theinternal and external physical magnitudes that may vary and influencethe energy performance of the system. In order to optimize the energyconsumption of the system, it is therefore preferable to vary the valuesof the set points depending on these internal and external physicalmagnitudes which may influence the operation of the system: this is therole fulfilled by the set point generator 32 shown in FIG. 2. The energyoptimization achieved by virtue of the method described here consiststherefore in varying these set points as a function of the values of theinternal and external physical magnitudes in order to determine, foreach operating point of the HVAC system 10, the optimum set points ofthe various regulation loops, with the aim of minimizing the energyconsumption of the HVAC system 10.

For this, a simulation in steady state of the HVAC system 10 will becarried out (step 106). This simulation in steady state is carried outon the basis of the modelling obtained by the description of the systempreviously carried out by means of the description software. The setpoint values of the regulation loops defined by the regulation boxes 70(corresponding to the set point applied to the input 30 of theregulation loop 26), and the values of the internal and externalphysical magnitudes are considered to be input variables for thissimulation of the HVAC system in steady state.

In order to carry out this simulation in steady state, the user may alsoenter, as input data, constraints on the values of the set points and onthe controls of the actuators (for example, for a motor, that the speedmust be between 30 Hz and 50 Hz). The user may also enter maximum and/orminimum values that one or more internal and external physicalmagnitudes can take.

Once all these data have been entered into the software, a computationmodule of the software will simulate the behaviour of the HVAC system insteady state, that is to say when the outputs, in this instance thevalues of the control signals intended to be applied at the input of theactuators, are stable over time (that is to say, for a control signal u,such that du/dt=0). When the HVAC system is operating in steady state,for each regulation loop, the set point value applied at the input ofthe regulation loop is substantially equal to the value of themeasurement that is applied at the input of the regulation loop (theerror computed by the regulation loop being in this case substantiallyzero).

The variables obtained at the output of this simulation in steady statecorrespond to the control signals intended to be sent to the input ofthe actuators of the HVAC system 10. Since these values are stable(steady state), the computation module can then compute, based on thevalues of these signals and on the electrical and thermal models of theelements of the HVAC system 10, the electrical power absorbed by theHVAC system 10 in steady state.

This simulation in steady state is therefore carried out by scanning thepossible values of the internal and external physical magnitude. Ifthere are n internal and external physical magnitudes, the set of valuesthat these physical magnitudes can take G1, . . . , Gn is called D, i.e.the domain of these physical magnitudes, such that: D=(G1, G2, . . . ,Gn).

The computation module of the software samples the domain D as a finiteset of points forming a set Dd (the discrete domain D). For each pointof Dd, the module determines the values of the optimum set points to beapplied making it possible to obtain a minimal energy consumption forthe system. This gives a function foptimum which associates, with eachpoint of Dd, a value such that:

foptimum: Dd={(G1, . . . , Gn)}->{(set point 1,set point 2, . . . )}

The value associated with each point of Dd is therefore determined sothat this value is that for which the energy consumption of the systemis lowest.

Then, each optimum set point value is evaluated in the form of amathematical function which will be for example, advantageously, apolynomial in G1, . . . , Gn. The coefficients of the polynomial canthen be determined by a least square method on the basis of the two setsDd and foptimum(Dd). This gives the values of the coefficients of eachpolynomial:

set point 1=P1(G1,G2,G3, . . . );

set point 2=P2(G1,G2,G3, . . . );etc.

These values of the coefficients therefore form a list of parameters forthe set point generator 32, which will be used for the programming ofthe controller or controllers of the control part 14 of the HVAC system10.

This simulation in steady state therefore makes it possible todetermine, as a function of the values of the internal and externalphysical magnitudes, the optimal values of the set points to be appliedto the regulation loops in order to minimize the energy consumption ofthe HVAC system 10 while observing the constraints imposed by the user.

A simulation of the system in dynamic state is then applied in order todetermine the parameters of the regulation loops 26 of the HVAC system10 (step 108). These parameters of the regulation loops are obtained bydetermining the transfer functions of each of the thermal elements,corresponding to the ratios between the values of the output physicalmagnitudes y and the values of the control signals u and of the physicalmagnitudes that are external and internal to the thermal element 20influencing the energy performance and the regulation performance of thethermal element 20.

To perform this simulation in dynamic state, each element 20 is assumedto be for example a system of the 1^(st) order with delay, that is tosay a system each of the transfer functions of which is of the type:

${\frac{y}{u} = \frac{K\; ^{{- \theta}\; p}}{1 + {\tau \; p}}},$

where

y: output physical magnitude

u: input signal (control signal or internal or external physicalmagnitude)

K: gain

θ: delay

τ: time constant.

Although a model of the 1^(st) order represents a good compromisebetween the accuracy of the results obtained and the complexity of thecomputations used, it is totally possible for the model used to be of anorder higher than the 1^(st) order.

Such a simulation in dynamic state makes it possible to evaluate, as afunction of the internal or external physical magnitudes and of thecontrols of the actuators (for example the outside temperature, thetemperature of the water of the pipe return, the water flow rate in thepumps, the rotation speed of a fan, etc), the values of the outputphysical magnitudes that it is desired to control (overheatingtemperature, high pressure, low pressure, flow rate etc), that willsubsequently be used to determine the parameters of the regulationloops.

For this, a computation module of the software varies values of signalsapplied on the inputs 22 and 23 (designed to receive the control signalsand the physical magnitudes) of the thermal elements 20 of the modelledHVAC system, that is to say applies transitory signals, such as controlsteps, on these inputs 22 and 23. These control steps are applied aroundthe operating point desired by the user, this operating pointcorresponding to the set points and to the physical magnitudes externalto the system: outside temperature, flow rates, etc.

The software carries out a sampling of the signals obtained at theoutput of the simulation and then determines, for each response obtained(that is to say for each control step applied), values of the variablesK, θ and τ of each transfer function. Finally, based on all the valuesobtained, and by applying for example a method of least squares, thecomputation module then determines the parameters K, θ and τ to beapplied for each regulation loop.

In a particular embodiment, it is possible to use the optimum set pointsobtained by virtue of the simulation in steady state as input data forcarrying out the simulation of the system in dynamic state. Thus, thissimulation in dynamic state is carried out at the particular operatingpoint desired by the user and for which the energy consumption of theHVAC system is minimal.

The regulation and energy-optimization parameters obtained by using thesimulations in steady state and in dynamic state are then used toprogram the controller or controllers of the HVAC system (step 110).

A functional module of the software can use these parameters to generatefunctional blocks, that is to say algorithms encoded in a programminglanguage, designed to be imported directly or by means of a programmingsoftware into the controller or controllers of the control part 14 ofthe HVAC system 10.

The functional blocks thus obtained based on the simulations in dynamicstate and in steady state are algorithms in the form of computer codesmaking it possible to carry out the regulation and energy optimizationof the various elements of the HVAC system 10.

When the controllers of the control part 14 are programmablecontrollers, the language of these codes then corresponds to theprogramming language of the controller or controllers of the controlpart 14 of the HVAC system 10, and corresponds for example to the Clanguage or to the “structured text” language. The code of eachfunctional block is then exported in the form of a file, for exampleencrypted, to an information-storage means (server, hard disk, USB key,CD-ROM). The file or files thus exported can then be imported into asoftware for programming the controllers and thus be used by the personin charge of programming the controllers (step 110). The programming maynotably consist in defining the interactions between the functionalblock or blocks relative to the energy optimization, and with thefunctional blocks relative to the regulation of the HVAC system 10. Theoutputs of the functional block or blocks relating to the energyoptimization, on which the optimum set points are delivered, willnotably be linked to the inputs of the functional blocks relating to theregulation, each regulation functional block being able to receive as aninput the optimum set point relating to the element designed to beregulated by this regulation functional block. The user then downloadsthe control program generated on the basis of the programming previouslycarried out into the memory of the programmable controller orcontrollers

In a variant embodiment, it is possible for the controller orcontrollers not to be programmable controllers, but parameterizablecontrollers. In this case, the programming is not carried out by theuser, the latter in this case transferring the list of parameters to thecontroller, these data being transferred directly (directly or via adata medium) into the parameterizable controller or controllers withoutbeing encoded in the form of algorithms. On the other hand, it ispossible for the parameters to be transferred in an encrypted manner soas, for example, to be able to lock certain functionalities as afunction of an offer level chosen by the user.

It is also possible for the regulation and optimization parameters to becopied by the user directly into the controller or controllers or into asoftware for programming the controllers. Here again, these parameterscan be supplied to the user in an encrypted form for reasons of lockingfunctionalities and/or in order to prevent errors when the parametersare copied into the controller or controllers, for example byintroducing error codes mixed with the parameters.

In the example described above, the simulation in steady state iscarried out prior to the simulation in dynamic state. However, it isalso possible for the simulation in dynamic state of the system to becarried out prior to or simultaneously with the simulation in steadystate of the HVAC system.

The algorithms used by the computation module will be a function notablyof the nature of the regulation loops (PID, predictive control, etc).Moreover, the mathematical models relating to the thermal and electricalbehaviour of the elements of the HVAC system used by the software toproduce the simulations in dynamic state and in steady state can beknown mathematical models, for example described in the thesis of P.Schalbart entitled “Modélisation du fonctionnement en régime dynamiqued'une machine frigorifique bi-étagée à turbo-compresseurs—Application àsa regulation” [Modelling the operation in dynamic state of a two-stagecooling machine with turbocompressors—application to its regulation],Ecole doctorale MEGA, 2006.

1-15. (canceled)
 16. A method for determining parameters for regulatingan HVAC system including thermal elements configured to be regulated byregulation loops, the method comprising: simulating in steady state ofthermal and electrical behaviour of the HVAC system modelled bymathematical models of thermal and electrical behaviour of the thermalelements of the HVAC system, computing energy consumption of the HVACsystem, modelled for different values of physical magnitudes influencingenergy performance of the thermal elements, and different values of setpoints to be applied at an input of the regulation loops; determiningvalues of the set points for which energy consumption of the modelledHVAC system is lowest; simulating in dynamic state the thermal andelectrical behaviour of the modelled HVAC system, computing values ofoutput physical magnitudes of the thermal elements; and computing, basedon the values of output physical magnitudes and for each of theregulation loops, the parameter values of the regulation loops.
 17. Amethod according to claim 16, wherein the simulating in dynamic state ofthe thermal and electrical behaviour of the modelled HVAC system iscarried out by varying values of input signals of the thermal elementsof the modelled HVAC system, computing the values of the parameters ofthe regulation loops being carried out based on parameters of transferfunctions of the thermal elements corresponding to ratios between thevalues of the output physical magnitudes of the thermal elements and thevalues of input signals of the thermal elements.
 18. A method accordingto claim 16, wherein the regulation loops are of predictive control. 19.A method according to claim 16, wherein the simulating in dynamic statethe thermal and electrical behaviour of the modelled HVAC system iscarried out by successively applying, on the inputs of each thermalelement, signal variations of a step.
 20. A method according to claim16, wherein the simulating in dynamic state the thermal and electricalbehaviour of the modelled HVAC system is carried out for values of theset points for which the energy consumption of the modelled HVAC systemis lowest.
 21. A method for regulating an HVAC system comprising thermalelements, comprising: thermal and electrical modelling of the HVACsystem by mathematical models of thermal and electrical behaviour of thethermal elements of the HVAC system; defining regulation loops in themodelled HVAC system, configured to be used by at least one controllerof the HVAC system, each regulation loop being associated with at leastone thermal element of the HVAC system and taking account of physicalmagnitudes influencing energy performance of the thermal element andquality of regulation of the thermal element; use of a method fordetermining parameters for regulating the HVAC system according to claim16; programming a controller of the HVAC system based on the values ofthe set points and on the values of the parameters of the regulationloops computed during the method for determining parameters forregulating the HVAC system.
 22. A method according to claim 21, whereinthe thermal and electrical modelling of the HVAC system comprises:describing the thermal elements of the HVAC system in a descriptionsoftware associating the thermal behaviour of each type of thermalelement with one of the mathematical models; describing, in thedescription software, hydraulic and/or electrical links between thethermal elements; and in which the defining the regulation loopscomprises describing, in the software: regulators capable of carryingout a closed-loop regulation of the thermal elements associated with theregulation loops; sensors for measuring output physical magnitudes ofthe thermal elements placed on hydraulic links, of which themeasurements are to be delivered as input signals to the regulators;pre-actuators associated with the thermal elements and configured toreceive as inputs control signals delivered by the regulators.
 23. Amethod according to claim 22, further comprising, prior to use of themethod for determining parameters for regulating the HVAC system,defining ranges of possible values of control signals to be delivered bythe regulators.
 24. A method according to claim 22, wherein thesimulating in steady state of the thermal behaviour of the modelled HVACsystem also determines values of the control signals to be applied atthe input of the thermal elements.
 25. A method according to claim 21,wherein the defining the regulation loops also comprises defining rangesof possible values of the set points of the regulation loops.
 26. Amethod according to claim 21, further comprising, prior to use of themethod for determining parameters for regulating the HVAC system,defining ranges of possible values of the physical magnitudes.
 27. Amethod according to claim 21, wherein, when the controller of the HVACsystem is a programmable controller, the programming of the controlleris carried out by: defining interactions, in a controller programmingsoftware, between algorithms relating to energy optimization of the HVACsystem based on the determined values of the set points and algorithmsrelating to the regulation of the HVAC system based on the computedvalues of the parameters of the regulation loops; generating a controlprogram encoding the algorithms and the previously defined interactions;loading the control program into the programmable controller.
 28. Amethod according to claim 21, wherein, when the controller of the HVACsystem is a parameterizable controller, the programming of thecontroller comprises entering determined values of the set points andcomputed values of the parameters of the regulation loops into thecontroller.
 29. A method according to claim 21, wherein the programmingof the controller of the HVAC system is carried out based on data inwhich the values of the set points and the values of the parameters ofthe regulation loops computed during the method for determiningparameters for regulating the HVAC system are encrypted.
 30. A devicefor determining parameters for regulating an HVAC system comprisingthermal elements configured to be regulated by regulation loops,comprising means for using a method for determining parameters forregulating an HVAC system according to claim 16.